Don’t choose the shape of the sunglasses Only, the quality control is more important

Summer is comming, and sunglasses can come in handy again! Many people use a pair of sunglasses for many years. As everyone knows, sunglasses also have a shelf life~ Generally speaking, the best use period of sunglasses is about two years, and it is best to replace them with a new pair after that.

First of all, the main wear and aging of sunglasses is the joint parts of the lens and the frame. There are currently three main types of lenses: resin polarizers, resin PC lenses (AC, CR39, and nylon are all temporarily classified into this category), and glass lenses. Lightweight and comfortable resin polarizer and resin PC lens are not wear-resistant, and will scratch over time. Many people do not know that the lenses are worn out, and relying on eye adjustment to try to see clearly will increase fatigue in the long run, resulting in decreased vision. Therefore, usually the lens should be put up to avoid scratches on the mirror surface.

Secondly, exposure to sunlight for a long time will reduce the ability of the lens to protect against ultraviolet rays and easily cause damage to the cornea. Through a simulation experiment, the researchers put the sunglasses under the sunlight simulator, 30 cm away from the light-emitting point, and continued to “expose” for 50 hours, and found that the UV protection ability of the lenses would be degraded. Tropical countries and regions have the highest levels of UV rays, which means that the UV protection of sunglasses degrades faster in these places. Even if the lens material of high-quality sunglasses is made of special materials, it will deteriorate over time. If the UV protection function of sunglasses is reduced, the cornea and retina will be damaged, and diseases such as solar keratitis and corneal endothelial damage will occur.

High-quality sunglasses can absorb or reflect UV light to block exposure to the eyes

  1. Mark “UV400”: It means that the isolation wavelength of the lens to ultraviolet light is 400 nanometers, that is, the maximum spectral transmittance of the lens below the wavelength of 400 nanometers cannot be greater than 2%.
  2. Mark “UV” and “UV protection”: it means that the blocking wavelength of the lens to ultraviolet rays is 380 nanometers.
  3. Mark “100% UV absorption”: It means that the lens has 100% absorption function for ultraviolet rays, and the average transmittance in the ultraviolet range is not more than 0.5%. Only those with the above-mentioned labels can be regarded as sunglasses with UV protection in the true sense.
  4. If you have dizziness, nausea, dazzling and other symptoms after wearing sunglasses, you should take them off immediately. Sunglasses belong to the series of flat mirrors, and are only allowed to have a diopter of plus or minus 8 degrees at most. Exceeding this error range is an unqualified product. According to market testing, nearly 30% of the diopter of sunglasses exceeds the error range, and some are even as high as 20 degrees. Consumers with normal vision wear this kind of sunglasses, just like wearing a pair of myopia or hyperopia glasses. After a summer, they will be “trained” into myopia or hyperopia patients by inferior glasses.

Second, buy sunglasses to go to regular stores. Some cheap sunglasses not only fail to filter out UV rays, but instead block the visible light, making the UV rays more noticeable. Be careful not to wear sunglasses for a long time, otherwise your eyes will get tired. Sunglasses should be removed from the outdoors. Don’t choose sunglasses with a large frame, it will increase the burden on the eye adjustment function and damage the eyesight.

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